THE EFFECT OF BED SLOPE ON WAVE CHARACTERISTICS

R.C. Nelson

Abstract

In all wave theories used in engineering applications it is assumed that the profile of the bed is horizontal which results in a symmetrical wave shape and velocity field, so that, strictly speaking, they can be applied only to this condition. Nearshore bottom profiles are, however, seldom horizontal, and a wave moving over a shoaling slope has an asymmetrical profile which is associated with an asymmetrical velocity field within the wave which, in turn, directly influences the movement of bed sediment. As a matter of necessity, but within reason, engineers have ignored the influence of bed slope on the wave theory used. This course of action was justifiable on many counts, not the least of which was that inaccuracies associated with the theories used were far greater than any inaccuracies introduced by ignoring bed slope parameters. However, wave theories developed in recent years have become increasingly accurate and reliable so that it may now be necessary to take account of bed slope parameters in applying these wave theories before further improvements can be made in the techniques used to predict wave-induced sediment transport.